Hi,I've implemented your solubility model in Java, using Weka architecture - class SolubilityModel inherits from Weka's Classifier. The code essentially mimics the table printed at http://onschallenge.wikispaces.com/SolubilityModel003, so it's pretty straightforward. The assumption is that the data sample (instance) has the same structure (number and meaning of attributes) as in the file onsc/ONSDataNumeric.arff. Below is the main part of the code, excluding several lines of headers:

I've run also a couple of tests of SolubilityModel using TunedTester. You can view all the results here. Your model performs pretty well! If you want to run more tests these are the settings that must be given in TunedTester:

Great interaction here and I am sure that this is really going to help a lot of people who are working and learning about solubility data. This post was really informative and reading about it, I am sure that the webservice is going to be just what is needed for people like us to come and refer. Hope everything goes well and as planned.